Conventional fuel storage tanks are generally made up of steel plates welded together with heavier, or thicker plates at the bottom and progessively thinner plates near the top. The cylindrical tanks are sometimes 120 feet in diameter and up to 50 feet in height. A concrete or crushed stone floor supports the steel floor of the tank, and a conical roof, also of steel, is generally supported not only by the cylindrical wall, but also by joists which are supported on internal columns resting on the steel floor.
The fuel stored in these tanks may comprise heavy oil, or even asphalt, and in northern climates must be continually heated so that the oil will flow. The temperature variation from the oil inside the tank to the atmosphere outside may be between 150 to 300 Farenheit degrees, and since the steel conducts heat very efficiently, there is a need for a system to economically and efficiently insulate these tanks. The steel plates in these tanks move as much as 6 inches when the tanks are filled or emptied, so the design of a practical system for insulating these tanks has not been commercially available.
The chief aim of the present invention is to provide a system for insulating fuel storage tanks, which system is not only economical, but which is also capable of withstanding the severe environmental conditions existing in the areas where such tanks have been erected.